Andy, is your Bronica an SQ-A -- not Ai -- I don't see that tab indicator on either of my "believed working" SQ-A bodies. (Maybe I have a problem I didn't know about. I've never actually used ME in taking photos with it.) My manual doesn't mention any indicator -- of course, the manual is not exactly a major encyclopedia!
Anyway, reckon that's why I was mystified by he earlier discussion.